Intermittent reversal of flow in a case of patent ductus arteriosus; a physiologic study with autopsy findings.

The direction of blood shunts between abnormally communicating ventricles or large vessels is dependent upon blood pressure differences in the adjacent structures, and upon the respective vascular resistance in both circulating systems distal to the communication. In a case of patent ductus arteriosus, physiologic measurements suggested that the direction of blood flow through the ductus was reversed intermittently during the systolic phase of the cardiac cycle. Pathologic studies confirmed the hypothesis by demonstrating the presence of "impingement" plaques on the aortic as well as on the pulmonary artery walls opposite the lumen of the ductus. They also gave information concerning the lesions in the pulmonary vascular bed which might be held responsible for the considerable increase in resistance, the pulmonary systolic hypertension and, attendant to it, the cyclic reversal of blood flow.